This invention is concerned with techniques for protecting optical systems from coherent radiation.
A coherent source of optical radiation, such as a laser, may supply light at an intensity which can damage sensitive parts of an optical system, such as a solid state detector array or the eye of a human viewer. Consequently, it is necessary to provide some means of controlling such harmful radiation in situations where it may occur.
Several characteristics are desirable for such a protective device. First, it must be fast enough to respond to incoming coherent radiation before any damage is done to the sensitive components. Second, the device should operate automatically to reject coherent radiation at any wavelength. Third, the device should be capable of operation over a wide band of wavelengths, i.e., rejection of different wavelengths of coherent radiation simultaneously is highly desirable. Fourth, the device must have a reasonable field of view, i.e., its angular range of operation should match those of conventional optical systems. Finally, the device should be as reliable as possible, with few, if any, moving parts required.